1. Field of Invention
The invention relates to covers for molten metal transfer cars. More particularly, the present invention concerns thermal insulation covers for transfer cars carrying molten metal.
2. Description of Prior Art
Transfer cars to move molten metals between various processing stations in a steel mill or foundry are well known. One problem related to this transportation system is the heat lost by the molten metal during transport. If the liquid metal cools below a certain point, the metal may, at a minimum, solidify within the car. Additionally, an alloy contained therein could undergo structural change that could adversely affect the capability of the metal to perform, as required.
One method of addressing this problem is to add additional heating furnaces along the processing line. The furnaces could then ensure that thermal loss is not so substantial as to affect the molten metal. However, such additional furnaces add to the processing time and cost.
A less costly alternative is to cover the central opening of the transport car. Since the greatest thermal loss occurs through this opening in the top of the car, a cover over this area will preserve the heat of the metal, because of its structural integrity, and maintain a heated transfer car after metal is removed. Traditionally, such covers have been made of metal, but metal covers act as thermal conductors. Therefore, such covers are poor choices to preserve heat.
A non-metal cover is taught in U.S. Pat. No. 4,381,855, issued May 3, 1983 to Ryan and entitled "TECHNIQUE FOR CONSERVING HOT METAL TEMPERATURE." Ryan teaches a flexible cover made of a thermal insulating material, which is commercially available under the trade name KAOWOOL. The KAOWOOL insulation material is held by a flexible screen, the screen and insulating material conforming to the size of the opening of the tanker car.
While the cover of Ryan lessens the heat loss from the molten metal of the car, it has drawbacks. Specifically, the flexibility of the Ryan cover makes deployment and removal of the cover cumbersome. Further, the constant exposure to the extreme heat of the metal disintegrates the screen, thus requiring frequent replacement of the screen.
What is needed is a non-metallic, non-heat conductive cover that is rigid, for easy deployment, and that is capable of withstanding the heat exposure. Further, a cover is needed that is conformable to the opening while being rigid and durable. It is to these needs that the present invention is directed.